Blower cooler



y 4, 1967 J. A. COWAN 3,329,415

BLOWER COOLER Filed Dec. 21, 1964 2 Sheets-Sheet 1 INVENTOR.

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July 4, 1967 J. A. COWAN 3,329,415

BLOWER COOLER Filed Dec. 21, 1964 2 Sheets-Sheel 2 /f' ff INVENTOR. fir; A (hazy,

United States Patent 3,329,415 BLOWER COOLER James A. Cowan, Marengo, Ill., assignor to Chicago Eastern Corporation, Marengo, IlL, a corporation of Illinois Filed Dec. 21, 1964, Ser. No. 419,995 6 Claims. (Cl. 26319) This invention relates in general to a forced air heating system. It deals more particularly with a system designed to draw in ambient air and force the air through a combustion zone for heating and subsequent circulation of the heated air in connection with agricultural crop drying and the like.

The use of a forced air heating system in agricultural crop drying, for example, is widespread. A forced air heating system of this type conventionally combines a blower unit and a gas burner unit suitably disposed in a housing so that the blower unit forces air through a combustion area where it is heated by burning gas and then directed into a crop drying enclosure. The present invention is primarily concerned with the eflicient utilization of the blower unit.

It is an object of the present invention to provide an improved forced air heating system.

It is another object to provide a forced air heating system wherein more efiicient utilization of its blower unit is achieved.

It is still a further object to provide a forced air heating system wherein the blower unit directs air more efficiently through the combustion zone.

It is still another object to provide a new and improved blower unit for a forced air heating system.

It is yet another object to provide a new and improved blower unit including a blower fan drive motor wherein optimum cooling of the motor is assured during operation.

It is yet a further object to provide a blower unit which directs driven air into cooling relationship with the motor and prevents recirculation of heated air into heating relationship therewith.

The foregoing and other objects are realized in accord with the present invention by providing a forced air heating system incorporating a blower unit which directs a portion of the driven air in a simple and inexpensive manner into cooling relationship with the driving motor of the blower unit. More particularly, a portion of the air driven by the blower fan past the motor housing is diverted through diverter assemblies associated with air flow straightening stator vanes into intimate contact with the blower motor to cool the motor efliciently.

In another aspect of the invention, a coning vane is arranged relative to the flow of air driven past the stator vanes and the generally frusto-conically shaped motor casing to force the bulk of driven air directly through the combustion zone in the forced air heating system. Furthermore, the generally frusto-conical casing is constructed so that heated air can not re-circulate into its confines to overheat the motor.

The invention, both as to its organization and method of operation, taken with further advantages and objects thereof, will best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a perspective view of a forced air heating unit embodying features of the present invention;

FIGURE 2 is an enlarged rear end elevational view of the heating unit illustrated in FIGURE 1;

FIGURE 3 is a sectional View taken along line 33 of FIGURE 2, with parts removed; and

FIGURE 4 is a sectional view taken along line 4-4 of FIGURE 3.

3,329,415 Patented July 4, 1967 Referring now to the drawings, a forced air heating unit embodying features of the present invention is illustrated generally at 10. The unit includes a cylindrical housing 11 formed of sheet steel or the like through which air is driven by a blower unit 15 mounted within the housing. The blower unit 15 forces air past a burner unit 16 which burns a separate mixture of natural or manufactured gas and air in the forced air stream and thereby heats the forced air before it leaves the unit 10. Suitable conduiting (not shown) normally is provided for directing the heated air to a crop drying enclosure or the like.

The blower unit 15 draws air into the upstream inlet 20 of the housing 11 through a guard screen 21 and annular mouth ring 22 mounted on the housing 11, and drives the air past the burner unit 16 and out of the downstream outlet 23. The downstream outlet 23 is normally connected to the conduiting (not shown) hereinbefore referred to and designed to connect the unit 10 to a corn drying bin (for example).

The blower unit 15 embodies features of the present invention and includes an electric motor 25 mounted within the confines of a frusto-conical motor casing 26 on a platform mount 27. The frusto-conical casing 26 is preferably fabricated of sheet steel or the like and is mounted concentrically within the housing 11 on radially extending stator blades 30. The frusto-conical casing 26 is open at its front end 31 and a radial blower fan 35 of well-known construction is mounted immediately in front of the opening 31 and concentric therewith on the forwardly extending output shaft 36 of the motor 25. The motor 25 is actuated and controlled from a conventional control box 37 mounted on the outside of the housing 11 through a shielded conduit 38 in a well-known manner.

The blower fan 35, which is conventional in construction, as has been pointed out, comprises a generally cir cular base plate 40 having angularly disposed vanes 41 arranged on its front face 42 in such manner that they direct air outwardly of the fan into an annular chamber 44 defined between the housing 11, the mouth ring 22, and the rotating blower fan 35. This air, the flow of which is indicated by the arrows A, is drawn into the rotating fan blades 41 through the annular mouth ring 22 and an annular inlet air enclosure wall 46 mounted in front of the blades 41 for rotation therewith.

As the driven air leaves the rotating blower fan 35 in a radial direction, it tends to swirl circumferentially in the chamber 44, of course, and tends to continue to swirl as it departs the chamber 44 along the generally frustoconical casing 26 toward the burner unit 16 and the downstream mouth 23 of the housing 11. The stator vanes 30 are constructed so that they straighten out this rotational flow of air and direct it toward the burner unit 16 with substantially only an axial component; a more efiicient airflow pattern for heating by the burner unit.

Referring specifically to FIGURE 2, it will be seen that there are fourteen of the vanes 30 arranged around the casing 26 between the casing and the housing 11. The vanes 30 are generally scoop shaped in cross section, as seen in FIGURE 4, and include an arcuate leading end section 50 and a generally planar trailing end section 51. The air swirling in the chamber 54 in a counter-clockwise direction (looking from the front end of the housing 11) as it leaves the radial lower fan 35, is caught by the arcuate leading end sections 50 of the stator vanes 30 and forced backwardly along the relatively straight rear end sections 51 of the vanes toward the outlet 23 of the housing 11.

The air travelling along the generally planar sections 51 of the stator vanes 30 near the outer ends of the vanes and immediately inside of the housing 11 encounters a frusto-conical coning vane 55 arranged, according to the present invention, to direct this outer sheath or portion of air inwardly toward the burner. unit 16 which is mounted immediately adjacent to and encircling the frusto-conical casing 26 adjacent its downstream end 56. The coning vane 55 comprises a series of slightly arcuate sheet metal sections 60 extending between the individual vanes 30 and canted inwardly from a leading edge 61 secured to the inner surface 62 of the housing 11 to a trailing edge 64 inwardly of the surface 62.

The burner unit 16 is preferably of the type illustrated in the co-pending Cowan application, Ser. No. 400,424, filed Sept. 30, 1964, entitled Blower, and assigned to the same assignee as the present invention, now US. Patent No. 3,193,265. It includes a burner ring 65 bracketed by an inner air deflector rim 66 and an outer air deflector rim 67 arranged in a manner described in the aforementioned copending application.-A substantial quantity of the air driven past the stator vanes 30 passes between the rims 66 and 67 past the burner ring 65 as a gas flame is burned downstream of the burner ring 65 to heat the driven air. Gas flow and ignition are controlled in a well known manner from the control box 68. According to the present invention, the downstream end 56 of the casing 26 is closed with a circular plate 69 to prevent recirculation of heated air back into the casing 26 to overheat the motor 25.

Operating in the environment described to this point, however, the motor could readily overheat even without being subjected to heated air circulation. If proper motor 25 cooling is not afforded, decreased blower efficiency results, as well as shorter motor 25 life, and a higher incidence of burnt out motors.

According to the present invention the motor 25 is properly cooled by diverting a portion of the air being driven past the. stator vanes into the interior of the casing 26 and intimate encircling relationship with the motor. This diversion of air is accomplished by forming generally airfoil shaped apertures 70 in the frusto-conical casing 26 adjacent several of the stator vanes 30 in the manner illustrated best in FIGURE 4. Air being driven past the stator vanes 30 is then directed through the several apertures 70 by baffie plates 71 which extend between the casing 26 and the inner surface 62 of the housing 11 and are inclined at an angle to the planar sections 51 of the stator vanes 30 in question. The trailing edge 72 of each baffie plate 71 is, in fact, secured to the trailing edge 73 of a corresponding planar section 51 in substantially air tight relationship while the leading edge 74 of the baffle plate is spaced therefrom the width of the widest portion of the aperture 70.

The leading edge 74 of each baffle plate 71 terminates immediately adjacentthe .forwardmost point of the corresponding aperture 70 and substantially in axial alignment with the juncture of arcuate and straight sections of the vanes 30. Accordingly, an access slot 7 S to the corresponding aperture 70 is defined between vanes 30v and bafl le plates 71.

There are three of these apertures 70 and cooperating baflle plates 71 situated around the periphery of the casing 26 and associated with prescribed stator vanes 30, as best illustrated in FIGURE 2. It has been found that three apertures and bafiie plates 71 are sufficient to provide a satisfactory amount of cooling air for the motor 25 under all operating conditions. In the arrangement illustrated, these apertures 70 and baffie plates 71 are spaced approximately 90 apart at the sides and top of the casing 26, the bottom of the casing being skipped because of the mounting 27 for the motor 25. However, any desirable number of these apertures and baffle plates 71 might be utilized.

The air which is formed into the casing 26 swirls around the motor 25 in cooling relationship. As more air is forced through the apertures 70, the air within the casing 26 escapes from the casing through the gap 80 between the plate 40 of the radial blower fan and the annular front open end 31 of the casing 26. Air in the casing 26 is assisted in its escape by the venturi effect created by the air from the blower fan 35 rushing past the gap 80. This air from the casing 26 is once again driven past the stator vanes 36 in the flow of driven air toward the burner unit 16.

The forced air heating unit 10 described and illustrated affords optimum cooling for its drive motor 25 at minimal expense. The casing 26 is simply apertured and little labor or expense is involved in mounting the battle plates 71. Furthermore the unit 10 provides for the direction of the bulk of driven air through the combustion zone. In addition, recirculation of heated air into the vicinity of the motor 25 is avoided.

While the embodiment herein is at present considered to be preferred, it is understood that various modifications and improvements may be made therein, and it is intended to cover in the appended claims all such modifications and improvements as fall within the true spirit and scope of the invention.

What is desired to be claimed and secured by Letters Patent of the United States is:

1. A forced air heating system, comprising: a housing defining a passage, a blower unit for forcing air through said passage, said blower unit including a blower fan driven by motor means mounted downstream of said fan in a casing so that air driven through said passage by said fan is driven past said casing, said casing being generally frusto-conical in configuration with its largest diameter in the upstream direction, stator vanes extending radially from said casing adjacent said upstream end thereof, a burner unit encircling said casing adjacent its relatively small diameter downstream end, and coming vane means associated with said stator vanes adjacent their outer peripheries for directing the peripheral sheath of air driven by said blower fan inwardly along said generally frusto-conical casing into a combustion zone associated with said burner unit.

2. The forced air heating system of claim 1 further characterized by and including aperture means in said casing adjacent at least one of said stator vanes for directing a portion of said driven air into intimate cooling relationship with said motor.

3. The forced air system of claim 2 further characterized in that the relatively smaller diameter end of said casing is closed to prevent the recirculation of heated air upstream into said casing to overheat said motor,

4. A forced air system, comprising: a housing defining a passage, and a blower unit for forcing air through said passage, said blower unit including a blower fan driven by motor means mounted downstream of said fan in a casing so that air driven through said passage by said fan is driven past said casing in a circumferentially swirling path around the axis of said casing, stator vanes extending radially between said casing and said housing, each of said stator vanes having a pressure side against which said circumferentially swirling air impinges, each of said stator vanes including an upstream portion arcuate in cross section and a downstream portion generally planar in cross section, said upstream portion curving in the direction of the pressure side of said vane, said downstream portion extending generally parallel to the axis of said casing, aperture means in said casing adjacent at least one of said vanes on the pressure side thereof for passing a portion of said driven air into said casing and intimate cooling relationship with said motor, baffie plate means joined to the trailing edge of said planar portion in said one vane and diverging from said planar portion in bracketing relationship with said aperture means, said bafile plate means and said one vane forming a trap with an open mouth facing transversely of said axis and directly into the circumferentially swirling flow of air so as to divert a portion of the air flowing past said casing through said aperture means into said casing.

5. The forced air system of claim 4 further characterized in that said aperture means extends along said one vane for the length of said downstream portion thereof, and said baffie means extends along said one vane for the same length.

6. The forced air system of claim 5 further characterized in that said casing includes a generally frusto-conical wall having its relatively large diameter at its upstream end and its relatively small diameter at its downstream end, said downstream end being closed whereby cooling air is provided from entering said casing through said downstream end, said cooling air entering said aperture means being afforded escape from said casing open front and between said casing and said blower fan.

References Cited UNITED STATES PATENTS 1,932,231 10/1933 Schmidt 230-117 2,294,586 9/1942 Troller 230122 2,866,594 12/1958 Quick 230-117 3,211,439 10/1965 Fahlberg 23619 3,217,976 11/1965 Downs 230-1 17 FOREIGN PATENTS 1,318,602 l/1963 France.

FREDERICK L. MATTESON, JR., Primary Examiner.

JOHN J CAMBY, Examiner. 

1. A FORCED AIR HEATING SYSTEM, COMPRISING: A HOUSING DEFINING A PASSAGE, A BLOWER UNIT FOR FORCING AIR THROUGH SAID PASSAGE, SAID BLOWER UNIT INCLUDING A BLOWER FAN DRIVEN BY MOTOR MEANS MOUNTED DOWNSTREAM OF SAID FAN IN A CASING SO THAT AIR DRIVEN THROUGH SAID PASSAGE BY SAID FAN IS DRIVEN PAST SAID CASING, SAID CASING BEING GENERALLY FRUSTO-CONICAL IN CONFIGURATION WITH ITS LARGEST DIAMETER IN THE UPSTREAM DIRECTION, STATOR VANES EXTENDING RADIALLY FROM SAID CASING ADJACENT SAID UPSTREAM END THEREOF, A BURNER UNIT ENCIRCLING SAID CASING ADJACENT ITS RELATIVELY SMALL DIAMETER DOWNSTREAM END, AND CONING VANE MEANS ASSOCIATED WITH SAID STATOR VANES ADJACENT THEIR OUTER PERIPHERIES FOR DIRECTING THE PERIPHERAL SHEATH OF AIR DRIVEN BY SAID BLOWER FAN INWARDLY ALONG SAID GENERALLY FRUSTO-CONICAL CASING INTO A COMBUSTION ZONE ASSOCIATED WITH SAID BURNER UNIT. 